+---------SUBJ:V-N--------+                     
      +----COMP:N-N(of)---+     +--COMP:V-N(in)--+    
      |            +MOD_AT+     |         +MOD_AT+    
      |            |      |     |         |      |    
 Expression of __NODE__ mRNA occurs in __SP__ spleen .
COMP:N-N(of) (expression,mRNA)
MOD_ATT:N-ADJ (mRNA,__NODE__)
SUBJ:V-N (occur,expression)
COMP:V-N(in) (occur,spleen)
MOD_ATT:N-ADJ (spleen,__SP__)